?-Poly-l-lysine and nisin A act synergistically against Gram-positive food-borne pathogens Bacillus cereus and Listeria monocytogenes

Aims: To test ε-poly-l-lysine and nisin A for possible synergistic activity against selected food-borne pathogens and food spoilage organisms. Methods and Results: Synergistic activity was observed against Gram-positive Listeria monocytogenes and Bacillus cereus cells and spores of B. cereus in 96 well plate assays. However, nisin A had no effect alone or in combination with ε-poly-l-lysine against Gram-negative Escherichia coli cells. In addition, when tested against yeast Zygosaccharomyces bailii, nisin A and partially inhibitory concentrations of ε-poly-l-lysine antagonized each other. Conclusions: Nisin A and ε-poly-l-lysine showed synergistic activity against B. cereus and L. monocytogenes. Significance and Impact of the Study: The application of nisin A and ε-poly-l-lysine is a promising all-natural method of controlling Gram-positive food-borne pathogens, spores and spoilage organisms.